Orientation and temperature dependence of dielectric and electromechanical properties of Mn-doped (Li,Na,K)(Nb,Ta)O₃ single crystals were investigated. Samples exhibited very low dielectric losses, with tanδ between 0.03 and 0.05 over a broad temperature range between room temperature and 480 °C. Influences of the crystallographic structure and external electric field on polarization and strain parameters are discussed. The orientation-dependent electrical properties were ascribed to the anisotropic polarization rotation in the crystals. Higher maximum polarization, coercive field, and negative strain were achieved when the electric field was oriented along one of the spontaneous polarization directions. The highest maximum unipolar strain of 0.42% (at 3 kV/mm) and the normalized strain d₃₃^* of 1391 pm/V were obtained in the [001]_PC-oriented sample at 100 °C, which was much higher than the values obtained for the [110]_PC-oriented sample. Further insight of the phase transition behavior is given by comparing the temperature-dependence of the small- and large-signal dielectric and piezoelectric properties. The observed changes are rationalized by the different increase rates of the dielectric permittivity and piezoelectric coefficients with temperature.

Magnetoelectric voltage tunable inductors (VTIs) offer a new paradigm for power electronics circuit design. Here, air-gapped VTIs are demonstrated exhibiting a large inductance tunability of 220% with applied fields under 20 kVcm ^-1 and operational stability up to 5 MHz that covers the full frequency range of the state-of-the-art power electronics. The design of air-gapped VTI comprises of two C-shaped ferrite cores, one permeability-variable magnetic flux valve (MFV) in between C-shaped cores, and slotted air gap between cores and MFV. The tunability of VTIs is achieved through the electric field modulation of permeability in the MFV based on the magnetoelectric effect. There is a tradeoff between the tunability and saturation current. The introduction of air gap significantly reduces the tunability but provides methodology toward increasing the saturation current and power handling capability due to the increased reluctance. The inductance and tunability reduces by 50% with increase in the air-gap width from 0.07 mm to infinity (condition with no C-shaped cores). Phase field simulations demonstrate that the air gap affects the magnetization, permeability, and tunability of VTIs by tailoring the demagnetization field that further influences the magnetic domain rotation process. VTIs with increased frequency range and saturation current will strengthen the continued development of tunable power electronics.

A distinct terrace edge current has been detected for the first time in a quasi-2D perovskite via charge gradient microscopic (CGM) measurements, which is due to the structural asymmetry at the edge in these materials.

Crystallographic grain-oriented ceramics (also referred to as textured ceramics) are known to exhibit a high soft piezoelectric response. However, the role of texturing in hard piezoelectric materials is not well understood and it has been difficult to obtain a balance of hard and soft properties in the same material. Here, we investigate the hard and soft piezoelectric behavior of [001]_PC-textured 0.05Pb(Mn_1/3Sb_2/3)O₃-0.95[0.4Pb(Mg_1/3Nb_2/3)O₃-0.25PbZrO₃-0.35PbTiO₃] (PMnS-PMN-PZT) ceramics to illustrate the influence of texturing degree. The results demonstrate that textured PMnS-PMN-PZT ceramics exhibit a 170% higher longitudinal mode piezoelectric coefficient (d₃₃) with only 16% reduction in the mechanical quality factor (Q_m). Random PMnS-PMN-PZT ceramics were found to exhibit a d₃₃ of 259 pC/N and a Q_m of 982, while textured ceramics sintered at the same temperature demonstrated a d₃₃ of 445 and a Q_m of 824. Electric field dependent x-ray diffraction is utilized to confirm the existence of internal bias generated from defect dipoles, providing the signature for hard behavior. Temperature dependent measurement of d₃₃ and Q_m for textured PMnS-PMN-PZT ceramics indicated high stability up to 120 °C.

(K,Na)NbO3-based ferroelectric single crystals have recently underwent a substantial development, resulting in improved crystal quality and large piezoelectric coefficients, exceeding 700 pC/N over a broad temperature range. However, further development necessitates a detailed understanding of the mechanisms defining the domain structure and its temperature evolution. This study presents the investigation of the crystallographic structure and domain configurations of a (K,Na,Li)(Ta,Nb)O3 single crystal over a broad temperature range. The crystal was grown by the Submerged-Seed Solution Growth technique and investigated using in-situ transmission electron microscopy, X-ray diffraction, dielectric measurements, and polarized light microscopy. The lattice distortion, structural phase transitions, and domain configurations are reported. A transition from the lamellar orthorhombic to the rectangular tetragonal domain structure is observed upon heating. Moreover, the milky optical appearance of the crystal was investigated and found to result from the presence of regions with different domain configurations and domain sizes. The formation of these regions is related to the growth defects, which govern the domain formation when cooling below the Curie temperature.